Aluminum Clad Steel Composite for Heat Exchanger Tubes and Manifolds

Abstract

A brazable composite metal material for a heat exchanger tube or manifold, a method of making the tube or manifold, and a heat exchanger made therefrom. The composite metal suitable for making the heat exchanger tube or manifold has one of an aluminized carbon steel, galvanized carbon steel, or steel wire mesh core roll bonded to at least one outer layer of a brazable aluminum alloy, such as type 3003 aluminum alloy. The method of making the heat exchanger tube includes the steps of (a) providing a core of one of an aluminized carbon steel, galvanized carbon steel, or steel wire mesh sheet or strip material; (b) placing at least one sheet or strip of brazable aluminum alloy material on the steel core; (c) roll bonding the aluminum alloy material to the aluminized surface of the steel core to form a roll bonded composite sheet or strip material; (d) forming the composite material to a desired configuration; and (e) joining abutting aluminum edges of the formed composite to form a fluid tight joined edge defining a shape having an open interior.

1 . A brazable roll bonded composite metal sheet having a steel core roll bonded to at least one layer of aluminum suitable for making heat exchanger tubes.  
   
   
       2 . The composite metal sheet of  claim 1  wherein the steel core is one of an aluminized carbon steel, a galvanized carbon steel, or a steel wire mesh and the aluminum of the outer layer is a brazable aluminum alloy.  
   
   
       3 . The composite metal sheet of  claim 2  wherein the brazable aluminum alloy is type 3003 aluminum alloy.  
   
   
       4 . The composite metal sheet of  claim 3  wherein a starting thickness of the aluminized carbon steel core is about 0.080 inch and the minimum starting thickness of each of the aluminum alloy is about 0.040 inch prior to roll bonding and a finish thickness of the roll bonded composite sheet is at least about 0.136 inch.  
   
   
       5 . A heat exchanger tube having a rectangularly-shaped cross-section with a joined flange on one side made from the roll-bonded composite sheet of  claim 1 .  
   
   
       6 . A method of making a heat exchanger tube or manifold comprising the steps of: 
 (a) providing a core layer comprising one of an aluminized carbon steel, a galvanized carbon steel, or a steel wire mesh sheet or strip material;    (b) placing a sheet or strip of a brazable aluminum alloy material on one or both sides of the core layer;    (c) roll bonding the aluminum alloy material to the core layer to form a roll bonded composite sheet or strip material;    (d) forming the composite material to a desired configuration; and    (e) joining abutting edges of the aluminum alloy in the formed composite to form a fluid tight joined edge defining a shape having an open interior.    
   
   
       7 . The method of  claim 6  wherein the joining step (e) is by one of brazing or welding.  
   
   
       8 . The method of  claim 6  wherein the manifold has a substantially rectangular or square configuration in cross-section.  
   
   
       9 . The method of making a heat exchanger tube of  claim 6  including the steps of removing surface oxides from the aluminized carbon steel or galvanized carbon steel material and from the aluminum alloy material and heating said materials prior to roll bonding step (c).  
   
   
       10 . The method of  claim 9  wherein the heating step is conducted at about 600° F.±50° F. in an ambient atmosphere.  
   
   
       11 . The method of  claim 6  wherein the roll bonding step is conducted with a preheated stacked array of aluminum alloy sheet or strip facing the aluminized carbon steel or galvanized carbon steel, and the roll bonding reduces the stacked array a total of about 15%.  
   
   
       12 . The method of  claim 11  wherein the roll bonding is conducted in a rolling mill in at least two passes through said mill.  
   
   
       13 . The method of  claim 12  wherein the roll bonding is conducted in two passes, wherein the first pass is at about a 2% reduction and the second pass is at about a 13% reduction.  
   
   
       14 . A method of making a heat exchanger comprising the steps of: 
 (a) providing a plurality of heat exchanger tubes and manifold members made according to the method of  claim 6;     (b) assembling the heat exchanger tubes with the manifold members, wherein the manifold members have a plurality of cut-out portions to receive open ends of the heat exchanger tubes therein, whereby the manifold members are in fluid communication with the heat exchanger tubes; and    (c) joining the heat exchanger tubes to the manifold members by brazing.    
   
   
       15 . The method of  claim 14  including the steps of providing a plurality of heat exchanger fins; and joining said fins to and between adjacent heat exchanger tubes.  
   
   
       16 . A heat exchanger manifold comprising a roll bonded metal sheet having an aluminized carbon steel core roll bonded between two layers of a brazable aluminum alloy.  
   
   
       17 . The heat exchanger manifold of  claim 16  wherein the aluminum alloy is type 3003 aluminum alloy.